Respiration Flashcards
what does respiratory pathway consist of ?
. nose . nasal cavity . paranasal sinuses . pharynx . larynx . trachea . bronchi . alveoli
What forms the conducting portion of the respiratory tract
The early parts of the respiratory pathway from the nose to the larger bronchioles
What is the function of conducting portion of respiratory tract ?
. no gas exchange occurs here
. air is cleaned , warmed , moistened
. Conducts air from outside into alveoli
What is in the respiratory part of tract ?
Small bronchioles and alveoli
What happens in the respiratory part of tract ?
Gas exchange - CO2/O2
Where does most inspiration occur
Through nose, can in mouth
What are paranasal sinuses
Spaces in head - air pushes in there
Air filled spaces/sinues that surround nasal cavity, they also contain blood vessel- (also serve to warm the air)
found in bones around nose
What is function of nasal cavity ( nose )
. conducts air to the pharynx ( connects atmosphere to nasal pharynx )
. contains olfactory receptors = sense of smell
. warms air
. moistens air
. cleans air
How is air conditioned
By warming, moistening and cleaning it
Why do you need to clean, moisten and warm air
CLEAN - Alveoli has delicate structures - want to get rid of the dirt from the alveoli
WARM - SA of lungs is huge, if you breathe in cold air, core temp decreases quickly so you want warm air into lungs
MOISTEN - If alveoli dry, they cant absorb respiratory gases - for gas exchange to happen, gases have to dissolve in something so has to be moist
What are olfactory receptors?
They line superior region of the nasal cavity - upper part of nose
Bipolar cells
produce action potential
what is the nasal cavity most lined with ?
pseudostratified ciliated epithelium containing goblet cells and nasal glands ( cilia on top )
What type of secretions are nasal gland
Mucous and Serous
What does nasal gland also contains
Antibacterial enzymes e.g. lysozome
What is the function of mucous in the nasal cavity ?
Traps impurities ( dust particles ) to clean the air /they help warm and moisten hair
What is the function of serous secretions in nasal cavity ?
Moisten the air
What is the function of superficial blood vessels in nasal cavity?
Warm the air
What is the function of cilia ?
Ciliated because impurities get trapped by mucus and need to get rid of mucus
The cilia of the nasal epithelium beat moving trapped impurities to the pharynx were they are swallowed
What happens in cold weather to the beating of cilia ?
Beating of cilia slows down and nose drips = runny nose
Cold/runny nose = secrete more antibacterial enzymes = more mucous = snotty nose
Mucus runs up front rather than go to back of throat
Cilia beat back towards pharynx in a rythmical manner - swallow mucous or spit it out
What do increased nasal secretions also account for
Stuffed up, runny noses following infection ( rhinitis )
What is the function of sensory nerve endings?
Trigger the sneeze reflex to expel impurities by complex series of muscle contractions
How many sensory nerve endings in nose
3
What happens to tears
Drained through puncta into nose and wafted back into cilia by pharynx - swallow tears
What is the function of paranasal sinuses ?
Decrease the weight of skull , they also warm and moisten the air
What happens after air passes through nasal cavity ?
Enters the pharynx ( which can be divided into different regions ) before entering larynx
What is larynx
Complex tube (modified part of the trachea) - which is made of muscle and cartilage. Not involved in respiration
What is the function of larynx?
Muscles contract to vibrate the vocal folds-produce sounds
What also goes down pharynx and larynx
Food
What is trachea
10-12 cm long tube connecting the larynx to the primary bronchi ( one going to left lung and one to right lung )
Where do primary bronchi enters and what happens there
Lungs
They subdivide into secondary bronchi and bronchioles
What lies next to trachea
Oesophagus - where food goes through
What is trachea surrounded by
C-shaped cartilaginous rings ( incomplete - doesnt go all way around )
What is function of C shaped cartilage rings
Allow trachea to change shape/diameter
stops trachea collapsing every time we eat
So we dont suffocate when we eat
what is the structure of trachea?
. Inner surface is covered by mucosa which is ciliated pseudostratified epithelium , and contains goblet cell
. The submucosa contain seromucous glands
-Ciliated
. Smooth muscle
Function of smooth muscle in trachea
Regulate flow of air by changing diameter of trachea/airway
Function of seromucous glands in trachea
Trap impurities and moisten the air
Produce antibacterial enzymes
Why is trachea ciliated
- Produce cilia - the cilia beat to move the trapped impurities to the pharynx- to swallow mucous
- When impurities are trapped by mucous, produced by goblet cells, they beat and move mucous collecting in lungs upwards through trachea into pharynx into mouth - swallow it
- Cilia grows back
How does the structure of the respiratory tract change as you progress downwards from the trachea
It simplifies
How does the structure of respiratory tract simplify as one progress downwards from the trachea?
. The cartilaginous rings are simplified to isolated plaques before disappearing
. The epithelium changes form pseudostratified to simple columnar to cuboidal to squamous in alveoli - height of alveoli decreases = EPITHELIUM SIMPLER
. The number of goblet cells decrease
. Number of cilia also decrease
. Elastic fibres remain constant through out system
What 3 structures are present in trachea
- Pseudostratified epithelium
- Goblet cells
- Extensive C shaped cartilage
What do the terminal bronchioles signify
End of conducting portion of respiratory tract
Why cilia still made when there is no mucous ?
Mucous falls down due to gravity
What is terminal bronchiole
Where alveoli and bronchiole link to conductive portion
What is the respiratory portion of the respiratory tract
. Terminal bronchioles which branch into smaller respiratory bronchioles , which are studded with isolated alveoli
. These lead to alveolar ducts containing more alveoli
. Finally leading to alveolar sacs made up of many alveoli
Where does gas exchange happen
In the alveoli
What is alveoli
Small thin bubbles that line broncioles
Summary of heart - process of blood supply to lungs
Right side out of heart coming out of right ventricle
Pulmonary artery - split into smaller and smaller vessels = arterioles - into network of capillaries - into veins and venuoles - until going back to left side of heart where you have pulmonary vein - 2 from left lung and 2 from right lung
What is the function of pulmonary artery?
Delivers deoxygenated blood to lungs
When does pulmonary artery stop dividing into smaller vessels
Until each alveolus is covered by a network of capillaries , before blood returns to the heart via pulmonary vein
What is each alveolus surrounded by ?
Dense network of capillaries containing oxygenated blood
What are the three types of cells that line the alveoli/separating the air in alveoli from the blood in the capillaries?
- The walls of the alveoli are mostly composed of simple squamous epithelial cells (type 1)
- Surfactant secreting cells (type of epithelial cells) (type 2)- produce surfactant
- Alveolar macrophages -to protect surface - wbc’s derived from monocytes
What is the function of alveolar pores between alveoli ?
Equalise the pressure within the lungs
What is always present in respiratory system and what is function of it
Elastic fibres
Provide elasticity
What is function of surfactant?
.contains antimicrobial proteins
. Lowers surface tension - this is because water molecules are more attracted to each other than to air/atmosphere , thus when alveoli is emptied of air they tend to collapse and walls stick together making it hard to reinflate
. Surfactant ensure that lungs don’t collapse when you breathe out by interfering with cohesiveness of water molecules
- Can get artificial surfactant
- Alveoli is lined with fluid, when you breathe out you empty alveoli of air
What does surfactant contain
Antimicrobial proteins/substances
What could cause infant distress syndrome or cot death
Premature babies die for no known reason
Sometimes surfactant producing cells are not produced until late in fetal development = premature babies are born without these surfactant producing cells = look like they are suffocated
what is the air:blood interface?
VERY THIN barrier that separates air in alveoli and blood in capillaries
Provides a barrier of minimal thickness for the diffusion of oxygen and carbon dioxide- gases diffuse through easily
What is the size of air:blood interface?
0.5 um
What is the air:blood interface composed of ?
- layer of surfactant - first thing that gases have to get through
- simple squamous epithelia of alveoli
- basement membranes on top of simple epithelium of alveoli
- Interstitial space - often fused together
- Basement membrane of endothelium of capillary
- Simple squamous epithelium of capillary
- Blood
What are the 2 simple squamous epithelium that seperates blood from air
Alveoli and capillary
Why is the alveoli fluid lined
So gases can dissolve - for gas exchange to happen
How does gas move
From an area of high pressure to an area of low pressure
What is Dalton’s Law
In a mixture of gases , the total pressure exerted is equal to the sum of partial pressure of individual gases
Gives you partial pressure for each gas
What is normal atmospheric pressure?
760mmHg - millimetres of mercury
How much can a column of mercury be pushed up vaccum
Weight of all air on top of us is enough to push column of mercury up by 760mmHg in vaccum
What is partial pressure of O2/CO2 in atmospheric air
partial pressure of oxygen is 21% of 760 = 160mmHg
partial pressure of carbon dioxide is 0.3% 0f 760 = 0.3mmHg
What is compostion of atmospheric air
O2 = 21%
CO2 = 0.04%
N2 - 78%
How is the partial pressure of oxygen and CO2 different in alveoli to atmosphere
the partial pressure of oxygen is lower and the partial pressure of carbon dioxide is higher in the alveoli compared to the atmosphere , this is because alveoli contains stale air and oxygen is absorbed while carbon dioxide is given off
Why does oxygen diffuse into blood and carbon dioxide into the capillaries ?
Blood arriving at the lungs is poorer in oxygen and richer in carbon dioxide than the alveoli
Why does oxygen diffuse into tissue and carbon dioxide into blood?
Blood arriving at the tissue has a higher partial pressure of oxygen therefore diffusing into tissue and lower partial pressure of carbon dioxide than the tissue
Explain what happens to oxygen and carbon dioxide at lungs ?
Oxygen diffuses into blood
carbon dioxide diffuses out blood
What happens to oxygen and carbon dioxide at tissue?
Oxygen diffuses into tissue
carbon dioxide diffuses out into blood
Which gas has higher partial pressure difference
Oxygen levels - partial pressure difference between O2 levels is much greater than for CO2
How many times is CO2 more soluble than oxygen
20x
What is Henrys Law
Gases dissolve in the fluid within the alveoli in proportion to their partial pressure
How is most O2 transported ( 98.5% )
in combination with heamoglobin in red blood cells
what is heamoglobin composed off ?
4 polypeptide chains , each bound to a haem group,
the iron in each haem binds a molecule of oxygen
Central element of haem group = Fe
How is carbon dioxide distributed in the body?
. 7-10% of carbon dioxide is dissolved in the plasma
. 20% is bound to the globin portion of heamoglobin
. 70% is dissolved in plasma as bicarbonate ion - mostly
What do lungs sit in
Pleural cavity of thorax
What are lungs surrounded by
Double layered serosa ( membrane ) , the pleura
What is function of pleura
Secretes a fluid - in between the gap of the 2 pleuras that fills the pleural cavity
What is function of pleural fluid
the fluid lubricates the movement of the lungs and surface tension ensures the lungs adhere to the walls of the thorax.
when the thorax moves so do the lungs
enables lungs to move in a frictionless way against bone and due to surface tension, lungs stuck to ribs and surrounding bony structures- when thorax moves so will lungs
what is boyles law?- mechanics of breathing
The pressure of gas is inversely proportional to its volume
so decreasing volume with same amount of gas increases collisions and increases pressure
Large vol with given amount of gas - gas molecules dont bump into each other or walls very often = pressure is low
What is another mechanic of breathing
A gas will move from an area of high pressure to a region of low pressure
What are the 2 main muscles involved in pulmonary ventilation?
. Intercostal muscle that join the ribs
. The diaphragm that separates the thorax from abdomen
What is diaphgram
Dome shaped sheet of muscle
What happens to lungs when vol of lungs increaes
Pressure decreases = air into lungs
what happens during inspiration (inhalation)?
. thoracic volume increases
. external intercostal muscles contract , raise the rib cage , expanding the thorax- increasing throaic volume ( front/back direction)
. the diaphragm contract ,flattens expanding the thoracic volume ( up/down direction)
. the pressure in the lungs falls below atmoshperic pressure ( as their volume has increased and pressure decreases)
and air enters the lungs
Summary of inspiration
Raises intercostal muscles Flattens diaphgram Increaes thoracic vol Decreaes lung pressure Air comes in lungs
How much is thoracic dimensions changed by during inspiration?
. Thoracic dimensions are only changed by a few mm in each direction , this is enough to change the volume around 500 ml = the normal amount we inspire every breath
During forced inspiration volumes are increased as secondary muscle e.g. scalenes, pectorals produce bigger volume.
How much can we inspire when we take a deep breath
Up to 3/4 litres
What happens during expiration ( exhalation)
. Inspiratory muscles relax and the elasticity of the thorax decreases its volume
. Pressure within the lungs increase above atmospheric pressure forcing air out
-Passive process
Summary of expiration
Flattens intercostal muscles
Decreases thoracic vol
Increases lung pressure
Air out lungs
What happens during forced expiration?
Abdominal muscle are forced against the diaphragm and internal intercostals pull down the ribs
What are the different resipiratory volumes
. tidal volume - normal breath
. inspiratory reserve volume - amount of air that can be inspired forcibly beyond tidal volume
. expiratory reserve volume - amount of air that can be expired forcibly beyond tidal volume
. vital capacity - biggest possible breath
. residual volume- air that cannot be expelled
What does residual volume show
Always get some air in lungs - can never be fully empty - need continous gas exchange othrerwise lungs would collapse - cant inflate
Generation of respiratory rhythm
. Basic ryhthm of respiration is generated in a group of neurons in the pons of the brainstem called the ventral respiratory group (VRG)
. VRG uses pacemaker neuron like in the heart and stomach via a.p
. inspiratory neurons in the VRG stimulate the diaphragm and external intercostal muscle
- Neurons in the dorsal respiratory group (DRG) receive input from peripheral stretch receptors and chemoreceptors and modulates the rhythm set by the VRG
- pontine respiratory system (PRC) modify the activity of VRG ( during speech , sleep and exercise)
how is respiration modulated to suit the body’s need ?
. central and peripheral chemoreceptors respond to low oxygen and high carbon dioxide levels to increase respiration. O2 levels increase = respiration decreaes
. proprioceptors = stretch receptors in muscle detect muscle activity = muscles are active it increaes respiration
. respiration can be influenced cortically
. stretch receptors in the lungs to inhibit respiration , preventing over inflation
. nociceptors in the lungs detect irritants and cause sneezes , coughs - complicated contractions
